The main goal of this monograph is to present the results of the research project accomplished between 2009-2012. The subject of this work was associated with theoretical considerations and with implementation of systems aimed at practical applications. The theoretical part is mainly devoted to methods for load identification in rail and road transport, and to parametric modeling and identification of structural modifications. The identification has been performed using gradient-based optimization methods, which - like the other approaches - can be used for local substructural monitoring by means of the developed virtual substructure isolation method. Among the most important developed practical solutions, one should mention the dynamic rail and road weigh-in-motion systems and the Moni-Most system. The first solution, installed in a roadway, measures online vehicle axial loads during their passages. The system enables preliminary selection of potentially overloaded vehicles, which contribute to the devastation of roads. A similar function is provided by the rail weigh-in-motion system, which can provide information to the owner of the rail infrastructure about passage of trains that exceed the admissible axial loads (and/or speed). The Moni-Most system is designed for monitoring of bridge structures based on vibrations caused by passing vehicles. Its implementation was integrated with the rail weigh-in-motion system, which provides information about the current load of the structure. The presented solutions are designed for technical condition monitoring of transport infrastructure, and they can be used to improve transport safety and reduce the failure rates. This study includes also selected problems related to structural health monitoring.